It's just as simple as adding the ".rss" extension to the URL.

https://cdn.masto.host/mastjohn1126com/media_attachments/files/116/089/590/686/951/189/original/c9529d7d72c86b35.mp4

download|http://filsofia.com/share/20260218-2026-0217-RSS-feed-from-Mastodon-hashtags---HQ.mp4